Field
Embodiments of the disclosure relate to methods of preparing compositions and materials useful in electronic applications, and in particular, useful as a single-piece tunable resonator.
Description of the Related Art
Various crystalline materials with magnetic properties have been used as components in electronic devices such as cellular phones, biomedical devices, and RFID sensors. Garnets are crystalline materials with ferrimagnetic properties particularly useful in RF electronics operating in the lower frequency portions of the microwave region. Many microwave magnetic materials are derivatives of Yttrium Iron Garnet (YIG), a synthetic form of garnet widely used in various telecommunication devices largely because of its favorable magnetic properties such as narrow line absorption at its ferromagnetic resonance frequency. YIG is generally composed of Yttrium, Iron, Oxygen, and possibly doped with one or more other rare earth metals such as the Lanthanides or Scandium. However, the supply of rare earth elements such as Yttrium has recently become increasingly restricted, thus resulting in correspondingly steep increases in cost. As such, there is a need to find a cost-effective substitute for rare earth elements in synthetic garnet structures that does not compromise the magnetic properties of the material and can be used for microwave applications.
Filters often need to be remotely reconfigured to different frequencies. This is currently done in cellular infrastructure base stations either off-site by removal and mechanical re-tuning, or on-site by electric motor-driven tuners activated remotely. An alternative method is the use of magnetically tuned resonators which are faster (micro-second tuning) than motor driven tuners (milli-second tuning).
Previous magnetically tuned solutions have used single crystal based YIG resonators either with YIG spheres or epitaxially deposited YIG on a lattice matched substrate. These solutions are large and expensive. Another approach is the use of composite resonators of dielectric and magnetic elements which are also large and expensive.